摘要
本文首次报导湘西黔阳一怀化地区隘口岩体全岩Sm-Nd等时年龄为890±104Ma,钕同位素初始比值为ε_Nd(T)=+1.63±1.90。样品的岩矿地球化学体系表明,岩体源自略亏损的地幔原区,并非为典型的反映大洋成因的蛇绿岩套,而更可能是晚元古宙江南碰撞造山带中段的一个组成部分,如弧后盆地开张初期产物。这一推论对研究华南地区构造演化史有重要指示意义。
Four whole rock samples from the mafic-ultramafic belt, Qiyang area, western Hunan have been collected for Sm-Nd dating, which yields a well-defined isochron age of 890+_104 Ma, Σ_(Nd) (T)=+1.63±1.90. The petrological and geochemical evidences suggest that the rocks were derived from a slightly depleted mantle source. It is unlikely they represent the members of a typical ophiolite suite. However, it may be explained as the consequence of opening of a backarc basin in the Late Proterozoic orogenic belt. This implication provides a new constraint on the tectonic evolution of South China.
出处
《地质科学》
CAS
CSCD
北大核心
1992年第4期391-393,共3页
Chinese Journal of Geology(Scientia Geologica Sinica)
基金
国家自然科学基金(949011)
瑞士联邦自然科学基金
关键词
铁质岩
钐
钕
年龄
镁铁-超镁
Qiyang area, Sm-Nd age, Late Proterozic collision belt
